Switchable support element for a valve train of an internal combustion engine

Abstract

A switchable support element ( 1 ) comprising a housing ( 2 ) in whose bore ( 4 ) an axially displaceable pressure piston ( 7 ) extends, said support element ( 1 ) comprising at least one coupling element ( 8 ) for an optional coupling of the pressure piston ( 7 ) in its axially extended position relative to the housing ( 2 ), said pressure piston ( 7 ) being biased in an outward direction from the housing ( 2 ) by at least one lost motion spring ( 9 ). The housing ( 2 ) ends in a solid bottom ( 10 ) which comprises a central aperture ( 12 ) that starts from its inner side ( 11 ) and is intersected radially by a reception ( 13 ) of the housing ( 2 ) comprising the at least one coupling element ( 8 ), the pressure piston ( 7 ) extending with an outer peripheral surface ( 14 ) of its head-side guide section ( 15 ) directly in the bore ( 4 ) of the housing ( 2 ), said guide section ( 15 ) connects in bore direction to a radially reduced center piece ( 16 ) that merges into a head-distal end piece ( 17 ) that is guided in the aperture ( 12 ) of the bottom ( 10 ), the lost motion spring ( 9 ) surrounds the center piece ( 16 ) and is supported at one end on the inner side ( 11 ) of the bottom ( 10 ) while acting at a further end against an underside ( 18 ) of the guide section ( 15 ), and the end piece ( 17 ) comprises an entraining surface ( 19 ) for at least one coupling element ( 8 ) for achieving coupling.

1. A switchable support element for a valve train of an internal combustion engine, said switchable support element comprising a pot-shaped housing that can be arranged with an outer peripheral surface in a reception of the internal combustion engine and in whose bore an axially displaceable pressure piston extends, a head of the pressure piston projecting beyond an edge of the housing, at least one coupling element for an optional coupling of the pressure piston in an axially extended position relative to the housing being associated to the support element, and said pressure piston being biased in an outward direction from the housing by at least one lost motion spring, wherein the housing ends in a solid bottom which comprises a central aperture starting from an inner side of the housing, the aperture is intersected in radial or secant relationship by a reception of the housing comprising the at least one coupling element, the pressure piston extends with an outer peripheral surface of a head-side guide section directly in the bore of the housing, said guide section connects in bore direction to a radially reduced center piece that merges into a head-distal end piece that is guided in the aperture of the bottom, the lost motion spring surrounds the center piece while being supported at one end on the inner side of the bottom and acting at a further end against an underside of the guide section, and the end piece comprises an entraining surface for at least one coupling element for achieving coupling. 
   
   
     2. A support element of  claim 1 , wherein the reception in the bottom is configured as a through-bore in which two piston-like slides serving as coupling elements are arranged opposite each other, these slides can be displaced radially inward in coupling direction through a mechanical spring means and radially outward in uncoupling direction through hydraulic medium pressure, the coupling elements possess on their upper sides a flattened portion for a face-to-face engagement with the entraining surface, which entraining surface is configured as an annular groove/annular segment in the outer periphery of the end piece. 
   
   
     3. A support element of  claim 2 , wherein the spring means is a segmental bent spring that is peripheral guided between edges of the through-bore in an annular groove in the outer periphery of the housing, and end regions of the spring means act in the coupling direction on radially outer front faces of the slides serving as coupling elements. 
   
   
     4. A support element of  claim 3 , wherein the end regions of the bent spring further form an anti-rotation device for the slides serving as coupling elements. 
   
   
     5. A support element of  claim 4 , wherein the outer front faces of the slides comprise a recess in the form of a longitudinal slot into which a complementary shaped portion of the end region of the bent spring engages for preventing rotation. 
   
   
     6. A support element of  claim 1 , wherein the center piece and the end piece of the pressure piston are made together in one piece and have a rod-like configuration, the center piece being connected to the underside of the separate guide section. 
   
   
     7. A support element of  claim 6 , wherein a stub-like extension protrudes from one of the guide section and the center piece and is retained in a reception of the other of the guide section and the center piece. 
   
   
     8. A support element of  claim 7 , wherein, for connecting the guide section to the center piece in a region of the extension and reception, a connection as a separable connection like a snap ring connection is used. 
   
   
     9. A support element of  claim 2 , wherein, peripherally offset to the through-bore for the slides in the housing, at least one hydraulic medium channel extends from the outer periphery of the housing radially inwards into the annular groove/the annular segment for forming a pressure chamber in front of the inner front faces of the slides serving as coupling elements, for displacing the coupling elements radially outward in uncoupling direction. 
   
   
     10. A support element of  claim 1 , wherein an axial displacement limitation for the pressure piston in an axially extended position is effected through a radial collar on the end piece, which radial collar cooperates with an annular step in an aperture of the bottom of the housing under the reception comprising the at least one coupling element. 
   
   
     11. A support element of  claim 10 , wherein an adjustment of coupling lash is effected or can be effected through a variation of thickness or height on the radial collar/on the annular step. 
   
   
     12. A support element of  claim 1  wherein the housing comprises a radially protruding element selected from the group consisting of a needle, a ball and a flattened portion, serving as anti-rotation device relative to a reception in the cylinder head. 
   
   
     13. A support element of  claim 1 , wherein the guide section of the pressure piston comprises a hydraulic lash adjuster.